Based on his work, this formula can be derived for ball diameter sizing and selection: Dm <= 6 (log dk) * d^ where D m = the diameter of the singlesized balls in = the diameter of the largest chunks of ore in the mill feed in mm. dk = the P90 or fineness of the finished product in microns (um)with this the finished product is ...
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Two new SAG milling models are developed in this work, able to predict power or specific energy consumption, including the usual design variables such as mill size; balls charge level, solids concentration in the SAG mill feed and % of critical speed, but adding a variable that represents the feed size distribution.
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The mill charge shape changes depending on the mill speed and this has direct impact on the a ... The process by itself becomes more flexible. Breaking rate. The breakage rate function shape of the SAG mill is largely governed by the mill load particle size ... Breakage rate as a function of particle size for mill speeds of 55%, % and 70% ...
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The SAG mill had a 68% ball charge and the power consumption was 8 kWh/t, which agreed well with the expected value. Problems. In an SAG mill the dimensions of the mill were m × m and the specific gravities of the mineral and that of the balls charged were and, respectively.
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Mill Charge. mill chargesteel rods − 6 × mm dia × m long steel rods plus. ... SAG mills of comparable size but containing say 10% ball charge (in addition to the rocks), normally, operate between 70 and 75% of the critical speed. ... The optimal hybrid system arrangement should satisfy and compromise the objectives of power ...
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Our system will ensure your mill operates at optimum charge level to save on energy and improve performance. ... You'll be able to reduce energy use while improving throughput at consistent product size. ... The AutoCharge system is primarily suitable for SAG mill balls (100150 mm). As each ball rolls through the counting chute, an electro ...
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Ball Size as Initial Charge. Commercial ball sizes 10 150 mm; Number, size and mass of each ball size depends on mill load and whether or not the media is being added as the initial charge. For the initial chargin of a mill, Coghill and DeVaney (1937) defined the ball size as a function of the top size of the feed,, dâ†"V = ...
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To obtain the optimal rotation speed of the SAG mill, we must calculate the motion of the particles ... [23] in the fields of charge motion and power draw, e ects of grinding media shape, breakage of particles, and so on. ... the size and number of particles in the SAG mill was mainly investigated based on discrete element method. For optimal ...
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Depending on the mill size the SAG mills draws between 2 MW and 17 MW. The product from the SAG mill is further reduced in size using pebble crushers and ball mills. Hence, typical gold or copper ore requires between and kWh per ton of energy to reduce the particle size. ... Millsoft is capable of simulating the motion of charge in the ...
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The size of a mill is usually characterized by the ratio "length to diameter" and this ratio most frequently varies from to The ... charge in the mill and a different impact of the milling bodies on the ground material. The grinding process can also take place in dry or wet conditions
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The variation of feed particle size significantly affects the overall process control, product quality, and economic performance of the mill [2] [3] [4]. Poor product quality from the AG/SAG mill ...
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The amount of pebbles passing through the grate increases with the angle of the grate. It is imperative to ensure the efficient removal of both slurry and coarse pebbles (critical size) in order to ensure the efficient operation of AG/SAG mills. Elimination of the above mentioned material transport problems will allow the mill to respond truly ...
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Generally, grinding efficiency depends on the behavior of the load inside the mill and it determines the share of various breakage mechanisms (Toor et al., 2013). Maintaining an optimum charge height and composition in a SAG mill remains one of the fundamentals for efficient mill processing (Royston, 2007).
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screening of sag mill feed. This paper presents and analyses a variety of plant data which illustrates the influence of feed size distribution variation on mill performance and discusses the reasons why ag and sag mills respond the way they do. From this analysis recommendations for optimum feed size distributions are made. I204 INTRODUCTION
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The modeling and simulation of semiautogenous (SAG) mills have been widely used in the design and optimization of mill performance in terms of its power draw, processing capacity and product size distribution. However, these models are solved under steady approximation and do not provide any information on mill charge distribution in real time. This paper attempts to characterize mill contents ...
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by volume load. Recent studies in the threefoot diameter SAG mill are instructive. The following graph shows the relevant facts as Figure 2. Figure 2: Pilot Plant kg/hr Vs Charge % by Volume This data is indicative of trends that were happening in the 3ft. diameter SAG pilot mill. They have not been proven in large commercial scale mills.
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For X = 600 m, PB = 4,197 kW. The total Ball milling section power draw would consequently vary from 8,394 kW (2 x 4,197 kW) for X = 600 m, to 8,462 kW (2 x 4,231 kW) for X = 610 m. A calculation for the SAG Mill power draw (PS) for X = 610 m follows. It is noteworthy that the SPI index has been conceived to include the SAG Mill overall ...
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When the SAG mill feed size ... (1975 mm) from a SAG mill. At the optimum pebble content of 25% by volume, a 25% saving in steel ball consumption and a 15% saving in energy consumption was ...
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The mill is a scaleddown replica of a commercial Koppers m x m (20 ft x 7 ft) SAG mill (see Fig. 1). The original design was developed by Vanderbeek and Herbst and was constructed by the Scale Model Makers of Cleveland, Tennessee. It is built of plexiglas and therefore allows the observation of the action inside the mill. The ...
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SAG Mill Feed rate, tlh 950 lBall charge, % 81 0 l~vera~e power, kW I~otal charge, % 1 24 1 1 ... Full mass flow and size balance around the SAG and ball mill circuits ii) Power response of the SAG and ball mills ... practicable and the ball and total charge at optimum levels 1070tlh was achieved. A full survey under these conditions was
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To obtain the optimal rotation speed of the SAG mill, we must calculate the motion of the particles and balls accurately. ... first applied DEM to the simulations of the charge motion in a 2D ball mill. Cleary and Sawley ... the relationship between the optimal speed and the size and number of particles in the SAG mill was mainly investigated ...
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control the weight in the SAG mill to promote optimum grinding. This strategy has been demonstrated to improve mill throughput by as much as 3%. When copper prices are high, producers look to increase production by eliminating process bottlenecks. At Minera Los Pelam bres, as at many mines, SAG mill through put limits overall production.
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A campaign of DEM simulations were performed by varying the mill size and charge particle size distribution to explore and understand the breakage environment in mills using DEM techniques. ... we develop series of DEM models that allowed simulating charge motion in SAG mills ranging from pilot scale to industrial scale with varied mill load ...
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In semiautogenous grinding (SAG), the grinding mill inventory, ( volume of total charge, volume of ball charge, etc.) is important in determining the optimum operating condition for maximum production (tph), minimum specific energy (kwh/t) or lowest cost (/t). A twodimensional graphical method is presented for determining the actual ball charge within the total charge when parameters ...
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The final plan was to increase the ball charge in the SAG and ball mill to 10% v / v and 27% v / v, respectively; set the upper limit of the operating power in the ball mill to 5800 kW; use a TRIO TC Series crusher (without a power/feed ratecontrolling device, but with a feed bin) to crush pebbles for recirculation back to the SAG mill feed ...
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Abstract. A research team from the University of Utah is working to make inroads into saving energy in these SAG mills. In 2003, Industries of the Future Program of the Department of Energy tasked the University of Utah team to build a partnership between the University and the mining industry for the specific purpose of reducing energy consumption in SAG mills.
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Batch grinding parameters a T min −1 γ α Λ β Φ 0 δ a T mm Table 2 Average input values for the fullscale mill and their corresponding interval ranges ...
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Power draw of the mill with the different lifters, 31% charge: 13% ball 18% rock, 70% critical speed. .
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Figure 1 shows a range of M4A SAG feed size distributions compared with an M1 feed size distribution. It is clear that the M1 material fragments very finely in the blast producing about 70% minus ...
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together with AG/SAG mill surface vibration to develop robust models for mill charge, feed and charge size, pulp density, and feed rate [14]. Zeng and Forssberg (1994) used ball mill vibrationacoustic signal and PCA to develop multiple regression models for monitoring process variables, such as feed rate, pulp density feed size, product size, and
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